1. Technical Field
The present invention relates to an image forming apparatus, a method for forming an image, and a program.
2. Related Art
An ink jet printer (hereinafter, also referred to as “printer”) is known as an example of an image forming apparatus. There is a printer which discharges ink droplets from a nozzle of a head unit while the head unit reciprocating in a main scanning direction and thus forms a printed image on a printing medium (for example, JP-A-2010-179626).
Miniaturization of discharged ink droplets is progressing in order to achieve high-definition of the printed image in the printer. There is a case where ink droplets having the miniaturized sizes are discharged in combination with ink droplets having large sizes in order to form large dots. Wind pressure by discharge of the ink droplets is also generated between the head unit and the printing medium in the printer in which the head unit described above reciprocates in the main scanning direction, in addition to wind pressure generated by movement of the head unit. In particular, in a case where ink droplets having large sizes are continuously discharged, there is a case where disturbance of large air flow is generated by the wind pressure accompanying the movement of the head unit and the wind pressure accompanying the discharge of the ink droplets. Therefore, in a case where the ink droplets having large sizes and the ink droplets having miniaturized sizes are discharged from the different nozzles from each other at the same time or continuously, there is a possibility that landing positions of ink droplets having the miniaturized sizes are deviated from the target position by disturbance of air flow as described above. When deviation of the landing position of ink droplets having the miniaturized sizes described above increases, density unevenness in the printed image is likely to be generated. There is a case where the density unevenness described above is similar to a pattern that can be formed on the surface of sandy land or the like by wind and thus is also referred to as “wind ripple”.
In a technology of JP-A-2010-179626, although the disturbance of air flow generated by the movement of the head unit is considered, disturbance of air flow generated by the discharge of the ink droplets is not considered at all. In a technology of JP-A-2010-179626, a movable member is provided on the head unit which generates air flow in a moving direction of the head unit in order to suppress the generation of the disturbance of air flow between the head unit and the printing medium. However, in a case where the moving member is added to the head unit, there is a possibility that new problems such as increase in size, weight, and manufacturing cost of the head unit and the printer, or the like are generated. Therefore, there is still room for improvement for a technology of suppressing generation of density unevenness in the printed image due to the deviation of the landing positions of the ink droplets.